Seems like Ogre3D 1.9 (this is what SR uses, right?) is quite well supported for the OpenHMD Virtual Reality API (http://openhmd.net/).Right now it does not yet support the recently released consumer head-sets, but most developer kits & Google Cardboard is supported. Judging from their Github branches ( https://github.com/OpenHMD/OpenHMD ) Occulus Rift and HTC Vive support is under active development as well. OSVR should also work more or less already as it is very similar to DK2.

I'm the developer of OpenHMDDemo and contributor to OpenHMD.I am open to help out creating a basic implementation in Stunt Rally if I have a accompanying developer from Stunt Rally to help me out in the codebase.

OpenHMDDemo is quite clear and the OpenHMD.cpp and .h files should be copy pastable to the project, most of the viewport and update stuff is in the main.cpp